The gypsy moth has been an important pest of hardwoods in the Northeastern United States since its introduction in 1869.

Established populations exist in all or parts of 19 states from Maine to Wisconsin and south to Illinois and generally in a southeasterly line from Illinois to northeastern North Carolina.

Oaks are the preferred host species for feeding caterpillars, but apple, sweetgum, basswood, gray and white birch, poplar, willow and many others serve as hosts. Gypsy moths avoid ash, yellow-poplar, sycamore, black walnut, catalpa, locust, American holly, and shrubs such as mountain laurel, rhododendron and arborvitae. Older larvae will also feed on a number of conifers such as hemlock, pines, spruces and southern white cedar.

Because the ecological range for this pest is extensive, there are still many states that can expect infestations in the future. Without intervention, this pest spreads about 13 miles per year. Artificial movement dramatically hastens the spread by the insect hitchhiking on items that are moved long distances such as nursery stock, vehicles, forest products, and outdoor household articles such as deck furniture. Federal and state regulations require that items to be moved from infested areas to uninfested areas must carefully be inspected and certified to be free of gypsy moth life stages.